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Tiny pellets that were supposed to have been made into plastic products have instead been found in their masses around Wellington's marine environment.

Sampling work that recovered hundreds of the tiny "nurdles" of virgin plastic from around the capital's waters and shores, along with large numbers of other microplastics, has highlighted the alarming toll pollution is now having on New Zealand's life-rich blue backyard.

Microplastics are small particles, less than 5mm in diameter, that are either manufactured at that size or result from the physical breakdown of larger plastic pieces.

While there's now plenty of evidence around the impact on animals and ecosystems from large plastic items, notably single-use bags, less is known about damage wrought by this much smaller scourge, now found in even pristine polar waters.

Scientists say pin-pointing the origin and distribution of microplastic pollution could make it possible to develop new strategies to combat the problem - and the few sampling studies so far undertaken here have shown the extent of it.

The most recent, made during the Pollution Use Resistance Education (PURE) Tour and Waka Odyssey Festival earlier this year, collected samples between Hawke's Bay and Wellington, with further surveys on the city's Oriental Bay beach.

A collaboration between Algalita South Pacific, 5 Gyres Institute, Tina Ngata and others, the sampling was done using specially-designed nets that were pulled behind ocean-going waka.

Some of the microplastics recovered from a trawl of Wellington Harbour. Photo / ESR

"Research into this area is fairly new to New Zealand and there is a lot to learn on how much plastic is out there, not only in the marine but also freshwater and terrestrial ecosystems, and understand the risks they pose to ecosystems, animals and potentially humans."

New Zealand has moved to ban microbeads, but the wider problem of microplastics couldn't be tackled in the same way.

Current legislation encouraged product stewardship and environmental responsibility at the beginning of a product's life cycle.